It's probably something where the government wanted to stop this deal for a number of reasons, and "national security" was the easiest justification where they already had a legal apparatus in place for doing so.
You jest, but the the world is well-aware of the risk - and possible consequences - of the top US office being compromised - or at least being held by someone who doesn't act in NATO's interests - and it's a sobering thought.
I'm not joking. Every traditional US partner suddenly realized during the Trump administration that their relation can end without warning. Now they're doing damage control.
